I periodically visit Google Analytics as it has the interesting responsibility of presenting a massive amount of data in a consumable form.  Given the numbers in the screen capture below, I derive more value out of interpreting their design decisions than I do analyzing my “readership” ;)

You’ll find much discussion on the relative merits of pie charts (or lack thereof).  Keeping the discussion focused on this display, the pie chart and area required to display it consume nearly 50% of the available width.  It’s the main draw here – large and full of bright, vivid colors.  It’s labelled with the percentages (kinda what the wedges should already be tellin’ ya, amirite?), forcing you to map between the various colors and labels several inches away.

If relative comparison is important (it is important for platform support decisions), what if we embedded a bar chart inside the table?

This allows easy comparison between the browsers themselves though I’m unsure if, without first looking at a visit percentage, it would be clear the row color consumes 50% of the table cell.  It may also not be as aesthetically pleasing than the tidy compartmentalization on the first image.  There are benefits to this approach, some of which come simply from choosing to use a bar chart in lieu of a pie chart: better area utilization, avoids having to map swatches/browsers to slices, etc.